More and more data users store large volumes of data remotely. Such an approach provides many conveniences for users, allowing users access to their data. Such access is, to a great extent, independent of a user's location and of the device a user may be employing to gain access to the data. Remote storage of data also allows users to share data with service providers who can use the data to provide better and more convenient services to the users.
The more data a user can store remotely, and the more data the user can share with other parties as desired, the more convenience a user can enjoy in the use of his or her data. However, much of a user's data is more or less private and a user wishes to be able to prevent access to such data by unknown or distrusted parties. On the other hand, learning the identities and trustworthiness of all parties that may handle the data deprives the user of much of the convenience that can be offered by remote data storage. It would be convenient for a user to be able to deliver his or her data without knowing which parties might be involved in handing or transfer of data from time to time, but protect sensitive data so that the data could be used only by parties satisfying criteria for access.